1. Field of the Invention
The present invention relates to industrial type robotic systems and more particularly to robot arms that have a three axis wrist formed with mutually perpendicular intersecting axes that lends itself well to servo control operation.
2. Description of the Prior Art
A wide variety of modern, industrial type robots have been advanced in recent years. For example U.S. Pat. No. 3,739,923 shows a wrist assembly for a robot that has dual intersecting axes movement and is mounted on a robotic type arm.
U.S. Pat. No. 3,543,910 has a wrist unit that provides a universal joint motion of a clamp tnat is used. The above mentioned patents do not include any continuously rotatable forearm that provides three degrees of freedom about intersecting axis. U.S. Pat. No. 4,076,131 shows an industrial robot having a rotating grip and a movable forearm as part of the robot arm.
U.S. Pat. No. 4,068,536 shows a wrist assembly for robot use which has a gear arrangement for operation of the wrist about three mutually perpendicular, intersecting axes. This device is made by Cincinnati Milacron and is commercially available. Additionally, commercially available robots include industrial robot systems made by the Bendix Robotics Division of Bendix Corporation, Southfield, Mich.; Moog Industrial Division makes a 3-axis Electrohydraulic Robot Wrist, and has literature out showing such wrist; Kuka Welding Systems and Robots sells an industrial robot that has a jointed arm for movement. A hydraulic wrist assembly for robotic use is made and sold by Bird-Johnson Company.
U.S. Pat. No. 4,047,448 shows a servo controlled robot head utilizing three servo motors mounted at the end of the forearm, and operating through concentric shaft drives and gear boxes to control motion about three mutually perpendicular intersecting axes. The use of bevel gears with the three direct drive servo motors at the outer end of the robot arm increases the loads that the robot arm must support, and generally leads to additional mechanism. Any additional drive linkages introduce control errors.
Additionally, a number of patents show general purpose remote control manipulators that have been in use for years, and these include the following patents:
U.S. Pat. Nos. 2,847,663, 3,108,498, 3,497,083, 3,631,737, 3,792,782, 3,821,498, 3,922,930, 3,985,238, 4,275,986, 4,283,764, 4,290,239, 4,096,953 and 4,305,028.